65 million years ago, dinosaurs answered this question with their own extinction, but what if a large-volume asteroid was replaced by a large-volume comet?
These dirty snowballs, made up of ice and other impurities, sent half an ocean at the beginning of Earth's formation, but in today's complex life on Earth, what will happen to the impact of a large-volume comet?
Astronomers Eugene and Carolyn Sumek from the United States spotted a comet near Jupiter in 1994 and named it SL9, but because the comet and Jupiter were so close together, the astronomical community soon discovered that it had been torn apart by Jupiter's gravity into 21 pieces, and that the 21 pieces of debris would soon fall into Jupiter, the most massive and bulky planet in the solar system.
Since this is the first time that humans have witnessed a celestial impact event, the astronomical institutions of various countries dominated by NASA have organized a luxurious observation lineup, in addition to the ground observatories distributed throughout the earth, the Hubble telescope in low-Earth orbit, and the Galileo probe that is rushing to Jupiter, have participated in the observation of the comet collision, and even Voyager I, which was 6 billion kilometers away from Jupiter at the time. Instructions were also received from ground-based control centers to analyze and record the electromagnetic situation at the time of impact with the planetary radio observation device it carried.
From 4:15 a.m. on July 17, 1994 to 8:12 p.m. on the 22nd, 21 fragments of SL9 crashed into Jupiter one after another, and the fragments numbered G reached 6 trillion tons of TNT equivalent, equivalent to 600 times the total equivalent of the human nuclear arsenal at this stage, and the single most powerful hydrogen bomb ever made by mankind, the Tsarist hydrogen bomb of the former Soviet Union, had a yield of only 55 million tons, and the power was not even comparable to the smallest fragment of SL9.
The three largest fragments of Comet SL9 have a total diameter of about 1.8 kilometers, and if the thermonuclear weapons now in human possession hit these asteroids in space, the full energy of the nuclear bomb will be released in the form of light and heat, directly vaporizing these uninvited guests from the depths of the universe.
If you wait until the comet enters the earth and then launch a nuclear weapon for defense, it is another situation, because the explosion of the nuclear bomb in the atmosphere will produce a violent shock wave, and the fragmented comet fragments will cause greater harm.
But even 65 million years ago, the 10-kilometer diameter asteroid did not make the earth life completely extinct, in the earth has appeared human civilization today, whether it is SL1, which has long been fragmented and disappeared in the jupiter cloud sea, or other "threatening celestial bodies" that may appear in the future, in fact, it is not terrible, after all, science and technology have been advancing, and human civilization will not stay on the earth forever, just like eggs will not be placed in the same basket.
As the third planet in the solar system from the inside out, the space position of the earth is not inferior, but there is another factor that really makes the earth give birth to life in addition to the space position, that is, Jupiter.
As the planet with the largest volume and mass and the largest number of moons in the solar system, Jupiter has always attracted wandering asteroids with its huge gravitational pull, and the more than 500,000 asteroids in the asteroid belt of the solar system between Mars and Jupiter are also stable because of jupiter's existence.
The escape velocity of the Earth is 11.2 km/S, so if an asteroid or comet from space is skimming over the Earth, it must be below 11.2 km/S to have a chance of being captured by the Earth and crashing into the Earth.
But celestial bodies in space rarely have such low velocities, so in theory, if an asteroid or comet wants to crash into the earth, its orbit can only coincide with the earth, but the probability is too small and too difficult.
The 380,000-kilometer distance between the Earth and the Moon is enough to trap all the remaining planets in the solar system, and the Sun and Proxima Centauri, 4.22 light-years away, are reduced in the same proportion, equivalent to two grapes hundreds of kilometers apart, and the analogy between an asteroid and the Earth is almost the same, and the "difficulty" of an asteroid hitting the Earth straight up is like shooting a coin on the west coast from the east coast of the United States.
Therefore, whether it is an asteroid or a human probe, when flying in the universe, there is no need to worry about hitting other celestial bodies, because space is really "space".